Don't install mpmath in the installation tests
Don't install mpmath in the installation tests

The installation should install it automatically, and we should test that.

madan96/sympy,jaimahajan1997/sympy,postvakje/sympy,Titan-C/sympy,madan96/sympy,jaimahajan1997/sympy,drufat/sympy,skidzo/sympy,rahuldan/sympy,kaushik94/sympy,ChristinaZografou/sympy,Titan-C/sympy,hargup/sympy,souravsingh/sympy,chaffra/sympy,hargup/sympy,sampadsaha5/sympy,yashsharan/sympy,kaushik94/sympy,postvakje/sympy,postvakje/sympy,drufat/sympy,souravsingh/sympy,drufat/sympy,yashsharan/sympy,rahuldan/sympy,aktech/sympy,Titan-C/sympy,sampadsaha5/sympy,souravsingh/sympy,chaffra/sympy,yashsharan/sympy,skidzo/sympy,aktech/sympy,madan96/sympy,hargup/sympy,kaushik94/sympy,ChristinaZografou/sympy,chaffra/sympy,aktech/sympy,sampadsaha5/sympy,skidzo/sympy,rahuldan/sympy,jaimahajan1997/sympy,ChristinaZografou/sympy